/*
 * Copyright (C) 2019 Adaptech s.r.o., Robert Pösel
 * Copyright 2014 Robert Theis
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.googlecode.leptonica.android;

/**
 * Extract rectangular regions.
 */
public class Clip {
	static {
		System.loadLibrary("jpeg");
		System.loadLibrary("pngx");
		System.loadLibrary("leptonica");
	}

	/**
	 * Extract a region from a Pix.
	 * <p>
	 * Notes:
	 * <p>
	 * This should be simple, but there are choices to be made. The box is
	 * defined relative to the pix coordinates.  However, if the box is not
	 * contained within the pix, we have two choices:
	 * <p>     (1) clip the box to the pix
	 * <p>     (2) make a new pix equal to the full box dimensions,
	 * but let rasterop do the clipping and positioning
	 * of the src with respect to the dest
	 * <p>
	 * Choice (2) immediately brings up the problem of what pixel values
	 * to use that were not taken from the src.  For example, on a grayscale
	 * image, do you want the pixels not taken from the src to be black
	 * or white or something else?  To implement choice 2, one needs to
	 * specify the color of these extra pixels.
	 * <p>
	 * So we adopt (1), and clip the box first, if necessary,
	 * before making the dest pix and doing the rasterop.  But there
	 * is another issue to consider.  If you want to paste the
	 * clipped pix back into pixs, it must be properly aligned, and
	 * it is necessary to use the clipped box for alignment.
	 *
	 * @param source Source pix
	 * @param box    Requested clipping region
	 * @return clipped pix, or null if rectangle doesn't intersect source pix
	 */
	public static Pix clipRectangle(Pix source, Box box) {
		long result = nativeClipRectangle(source.getNativePix(),
				box.getNativeBox());
		if (result != 0) {
			return new Pix(result);
		}
		return null;
	}

	// ***************
	// * NATIVE CODE *
	// ***************

	private static native long nativeClipRectangle(long nativePix, long nativeBox);
}